Underreamer



R. L. BURNS.

UNDE'RREAMER.

APPLICATION FILED NOV. 29, 1920.

Patented Jain. MI 1922,

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ATTORNEY R. L. BURNS.

Patented Jan. ML, 1922.

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R. L. BURNS.

UNDERREAMER.

APPLICATION FILED NOV- 29, I920.

Patented Jan. M1922.

3 SHEEISSHEET 3' INVENTOR,

BY A I Iii) v V ATTORNEY UNHTEID) stares EQBERT I4. BURNS, OF THE,GALIJFQRINIA.

UNDER ncense.

Specification of Letters Patent.

Patented Jan. 141 1922.

Application filed November 29, 1920. Serial No. 426,949.

To all whom it may concern:

Be it known that 1, ROBERT L. BURNS, a citizen of the United States,residingat Taft, county of Kern, State of California, have invented anew and useful Underreamer, of which the following is a specification.

This invention relates to underreamers, and is particularly directed tounderreamers such as are utilized in the process of drilling oil andother well bores by the reciprocatory or churn drilling method.

As is well known in this art, the wellboring or drilling tools which areemployed in the reciprocatory method of drilling, only drill a hole ofsubstantially the diameter of the interior of the casing. This leaves ashoulder or annular obstruction beneath the casing which must be removedbefore the casing can be lowered. For this urpose underreamers, providedwith expanslble cutters or'slips, are employed, said underreamers beinglowered through the casing afterv a period of drilling, with the slips1n contracted condition. Such underreamers are generally constructed sothat the cutters or slips automatically expand after passing the shoe orlower end of the casing, the casing being somewhat elevated above theshoulder to permit such expansion and to permit a commencement of theunderreaming operation.

The present invention is directed particularly to that type ofunderreamer referred to in the trade as the Bowl-type, wherein thereamer body is recessed upwardly from its lower extremity providing animperforate annular wall and a longitudinally extending cavity toreceive and confine the shanks of a pair of opposed cutters or slips,the shanks being movable vertically and tiltable Within the body cavityto permit the slips to expand to cutting position and to be contractedfrom such position. In this type of underreamer it is desirable that theshanks of the slips be relieved of the major portion of the strainsincident to the cutting operation, that the cavity of the body be ofminimum proportion so as to provide a relatively thick annular wall, andt at the cooperating bearing surfaces of the wall and the slips be ofsuch area and contour as to receive and transmit directly to the body,all strains and thrusts. At the same time the construction should besuch as to avoid as far as possible the formation of irregularities orpockets in the cooperating surfaces or faces of the body and of theslips, such irregularities and pockets being diflicult to form andtending to cramp and obstruct the slips and to form open spaces for thecollecting of sand and abrasive materials detrimental to the operationand life of the tool.

With the foregoing general requirements lll'l view, the object of theinvention is to provide an underreamer of the Bowl type, havingrelatively large cooperating bearing surfaces between the slips and thebody, to provlde perfect seats for the slips, to provide a constructionin which the wearing surfaces will to a large extent be protectedagainst the entrance of sand or other abrasive matter, and in which themajor portion of the strains and thrusts incident to an underreamingoperation are transmitted directly to the body.

Another object is to rovide an underreamer provided with shps havingcutting edges of extensivecircumferential span and to provide anunderreamer which will be superior in point of relative simplicity inconstruction and organization, taken in connection with reliability incollapsion, and expansion of the slips, positiveness of operation,simplicity and convenience in control and manipulation, compactness inform, durability as to the entire tool and particularly as to the lengthof effective life of the slips and other working parts, and which willbe generally superior in efficienty and serviceability.

Various other objects and advantages will be more fully apparent fromthe following detailed description of the accompanying drawings whichform a part of this disclosure, and which illustrate a preferred form ofembodiment of the invention.

Of the drawings:

Figure 1 is an elevation of the underreamer of the present invention,the slips being in expanded positions.

Fig. 2 is an elevation taken at right angles to Fig. 1.

Fig. 3 is an enlarged vertical section, showing the slips in expandedpositions.

Fig. 4c is an enlarged view, similar to the lower end ofFig. 2, showingthe body in section.

Fig. 5 is a vertical section similar to the lower portion of Fig. 3,showing the slips in collapsed position, a ortion of one slip beingbroken away to il ustrate the full contour of the opposite slip.

1 1 3.3. l -ig. 7 is a plan section on line X -X" showing the slips incollapsed position.

of Fig. 3.

with the working parts removed.

commodatea suitable more 1" which the spring rod may b ulled ownward inof setting the slips in col apsed position; The F1 3, above describedshank construction" and hig. 8 is a plan section on line X"-.-' X ofpivotal connection provides slip members,

ig. 9 is a Fig. 6 is a plan section on line X -X" of vertical Section online X9-X" ing, with a scissor-like movement;

Fig. 10 is a bottom plan view of the body bod is of the specificconfiguration shown f in 1 1, and may be formed by milling Fig. 11 is anelevation -similar to Fig, 1, straig t across the lower end'of the body,

-.With reference to the drawings, 1 desig grooves 20-20, the adjacentoutwardly and nates the body of the underreamer, and2 downwardly angledu -thrust.bearing surthe sub to which the body is joined, said faces21-21, and the intermediate expandsub having the usual tapered andthreaded ing lugs 22-22, there. being two such lugs pin 3 by which theunderreamer is attached (see' Fig. 10) by reason of the intersecting tothe string of tools in the usual nianner. cavity 4. The lugs serve topositively ex- 1 The body isrecessed upwardly from 1ts pand the slipsand. provide opposed sliplower extremity to form a substantiallyrecexpandin "and in-thrust bearing. surfaces tangular cavity '4; adaptedto receive thev 23-23, t e grooves 20-20 forming outrespective shanks ofthe slips and-the-lower thrust bearing surfaces 24-24 and the ad-' slipsupporting end of the spring rod or ditional up-thrust bearin surfaces25-25. mandrel 5. Said rod has a head 6 of rec- The upper surfaces 0tangular cross sectional contour correspond-- are contoured to closelyfit the bearing suring to the contour of the cavity 4, this prefaces ofthe body when in expanded posiventing the rod from turning, and acircular tion, they being rovided with transverse upper portionextendingupwardly through tongues 26-26 a apted to engage w1th1n -a,bore in the body, said bore having an the grooves 20-20 and providingangled enlarged upper portion providinga spring expanding and in-thrustbearing surfaces chamber 8. The upper end of the rod is 27-27,'andangled up-thrust bearing surscrew threaded to receive the nut 9 and afaces28-28 to engage the -up-t hrust bearing coil spring 10 surroundsthe ,rod within the surfaces 21-21 of the body.

The contour of the lower surface of the the slips 14- 15 operating intheir expanding and collapsthis providing two opposed transverse:

spring chamber, the'spring engaging the 'lhe body portionsof the slipsare of a bottom wall of the chamber and a washer half cylindrical crosssectional contour pro- 11' beneath-the' nut 9. viding cutting edges ofextension circum- Depending fromthe medial portion of the ferential spanand the' side walls of the rectangular head 6 ofthe sprlng rod 5 is aslips are-correspondingly grooved as at 30 flat tongue 12 carrying atransverse pivot to accommodate a retaining band or strap, pin 13 as ameans of pivotal support for the as indicated in dotted lines in Fig. 5,for slips 14-15. v the purpose of holding the slip in collapsed The slis 14-15 have upwardly extending position while the tool is beinginserted into flat shan slP-l5, said shanks being disthe well casing,according to a practice now posed 'to one side of the transverse centerswell known in the art. Near their upper of their respective slips sothat when assemends the slips have beveled shoulders 31, bled the shankof one slip will be positioned which when the underreamer is elevated toonone side of the tongue 12 and the shank cause 'a collapse of theslips, will engage of the opposed slip will be positioned on the thelower end of the casing, or casing shoe opposite side thereof, eachshank being pivto hold the slips stationary while the body otallyjournaled on an opposite end of the 1 is being drawn u wardly and camthe pivot pin 13 and the combined thicknesses slips inwardly to colapsed position for a of the two. shanks and the ton e e ualingwithdrawal of the underreamer from the the corresponding dimension 0 therectanwell. gular cavity 4, as indicated in Figs. 4 and 8. From theabove and with particular ref- Each shank, between its pivoted centererence to Figs. 5 and 11 of the drawin and the top of'its. respectiveslip, is of a and considering that the spring 10 is un er width equal tothe width of the cavity 4, tension, it will be evident that when the andabove such pivoted center the side adlmderreamer is lowered in. the wellcasing jacent said slip is vertically angled inwardly, beyond the bottomthereof, the slips, then as at 16, to permit a tiltin of the slip, bemfree to expand, will be translated upwhile the side opposite is relievedas at 17 war ly by the action of the spring 10, and to provide clearanceagainst binding on the by reason ofthe cooperative cam action of mouthof the, cavity. The tongue 12 extends the bearing surfaces 27-23 will bepositively downwardly into clearance recess 18 in the forced outwardlyduring such upward moveslips and has a transverse orifice 19 to acment.

' mosses the intermeshing tongues or grooves effectively prevent aripping out of the slips under excessive out-thrust strains. The angleddisposition of the up-thrust bearing surfaces is particularlyadvantageous in urging the slips to close en agement with the bodysurfaces when su jected to upthrust or in-thrust strains and contributetowards withstanding out-thrust strains.

The construction as above explained provides a bowl type of underreamerin which the central cavity has been reduced to a minimum diameter,leaving a thick strong bowl wall providing extensive bearing surfaces,and the slips are contoured to interlock in the grooves of the body andto provide a maximum span of cutting edge.

While the specific form of mechanism herein shown and described, isadmirably adapted to fulfill the objects primarily stated, in is to beunderstood that it is not intended to confine the invention to the oneform of embodiment herein disclosed, for it is susceptible of embodimentin various forms, all coming within the scope of the following claims.

What is claimed is follows:

l. In an underreamer, a body having an axial recess upwardly from itslowerextremity forming an imperforate bowl, a spring rod slidable withinsaid recess, a transverse pivot pin carried b the rod, a springfunctioning to elevate t e rod, and opposed slips having flat! shanksprojecting upwardly in overlapping relation and pivotally journaled onthe pivot pin, the body having transverse grooves in its under surfaceand the slips having transverse tongues for interlocking engagement withthe companion grooves.

2. In an underreamer, a-body having an axial recess upwardly from itslower extremity forming an imperforate bowl, the lower face of the bowlformed to provide transverse grooves adjacent opposite sides of therecess, expanding lugs between the ends of the grooves and outwardly anddownwardly extending transversely flat bearing surfaces outwardly ofeach roove, a rod slidable within the recess o the body, a springfunctioning to elevate the rod, a pivot pin carried by the rod, opposedslips having flat shanks projecting upwardly into the recess inoverlapping relation and pivotally supported on the pivot pin, the bodyportion of each slip having a transverse tongue and an adjacent bearingsurlface adapted to engage the companion groove and bearing surface ofthe body on one side of the recess.

3. In an underreamer, a body provided with a recess having four verticalside walls and extending upwardly from its lower extremity to form animperforate bowl, and an axial bore above said recess forming a springchamber, a rod slidable in the recess and extending into the sprinchamber, said rod having a head contoure to slidably fit within therecess and a flat tongue depending from the medial portion of the headand of a width substantially equal to the width of the recess, opposedslips having flat shanks extending upwardly on opposite sides of thetongue and pivotally journaled to swing thereon, the combinedthicknesses of the two shanks and the tongue being substantially equalto the corresponding dimension of the recess, and a spring in the springchamber functioning to elevate the rod, the body having means forseparating the slips during their upward movement.

4:. In an underreamer, a body having a substantially rectangular, recessupwardly from its lower extremit forming an imperforate bowl and an axiabore enlarged at its upper end to provide a spring chamber, the lowersurface of the body having trans versely disposed grooves on opposltesides of .the recew and formed to provide outwardly and downwardlyangled bearing surfaces outwardly from said grooves, a rod slidable inthe recess and bore, said rod extending upwardly into the spring chamberand having a rectangular head slidable in the recess and a flat tonguedepending from said head, a spring in the spring chamber functioning toelevate the rod, and opposed slips having shanks extending upwardly intothe recess on opposite sides of the tongue and pivotally connectedthereto, the slips each having an upstanding transverse tongue adaptedto fit into the companion groove of the body and an angled bearingsurface extending outwardly and downwardl from said tongue and adaptedto engage t e companion bearing surface of the body.

Signed at Taft, California, this 22d day of November, 1920.

. ROBERT L. BURNS.

Witnesses:

MARGUERITE CARMAOK, T. J. OBRIEN.

